Icriodus

P₁ elements and denticle of ramiform element from Icriodus iowensis, from Dzik (2002).

Belongs within: Balognathidae.

Icriodus is a genus of conodonts known from the Devonian, characterised by the possession of a lanceolate, nodulose or ridged, P₁ element. The remaining elements in the apparatus were mostly tiny and coniform (Sweet 1988).

Characters (from Hass 1962, for P₁ element only): Lanceolate, steep-sided in oral view; carina flanked on each side by a row of nodes or short transverse ridges; lateral process may trend outward from pulp cavity located at expanded posterior end of unit.

Icriodus Branson & Mehl 1934 D02
    |--*I. expansus Branson & Mehl 1934 D02
    |--I. alternatus Branson & Mehl 1934 D02
    |--I. angustoides S88
    |--I. angustus Stewart & Sweet 1956 (see below for synonymy) WSQ86
    |--I. arkonensis S88
    |--I. brevis Stauffer 1940 D02
    |--I. corniger Wittekindt 1965 D02
    |--I. cornutus N79
    |--I. culicellus (Bultynck 1976) [=Caudicriodus culicellus] WSQ86
    |--I. curvirostratus N79
    |--I. elegantulus Stauffer 1938 D02
    |--I. hadnagyi S88
    |--I. introlevatus N79
    |--I. iowensis Youngquist & Peterson 1947 D02
    |--I. kielcensis Dzik 2002 D02
    |--I. latericrescens M62
    |    |--I. l. latericrescens N79
    |    |--I. l. beckmanni N79
    |    |--I. l. bilatericrescens N79
    |    |--I. l. huddlei N79
    |    `--I. l. robustus N79
    |--I. mowitzaensis S88
    |--I. obliquimarginatus N79
    |--I. orri Klapper & Barrick 1983 KU04
    |--I. regularicrescens S88
    |--I. stephensoni Sparling 1983 KU04
    |--I. struvei Weddige 1977 D02
    |--I. subterminus Youngquist 1947 D02
    |--I. symmetricus Branson & Mehl 1934 D02
    `--I. woschmidti W97

Icriodus angustus Stewart & Sweet 1956 [incl. Acodina curvata Stauffer 1940, Drepanodus inoptinatus Bultynck 1970] WSQ86

*Type species of generic name indicated

REFERENCES

[D02] Dzik, J. 2002. Emergence and collapse of the Frasnian conodont and ammonoid communities in the Holy Cross Mountains, Poland. Acta Palaeontologica Polonica 47: 565–650.

[KU04] Klapper, G., T. T. Uyeno, D. K. Armstrong & P. G. Telford. 2004. Conodonts of the Williams Island and Long Rapids Formations (Upper Devonian, Frasnian–Famennian) of the Onakawana B Drillhole, Moose River Basin, northern Ontario, with a revision of the Lower Famennian species. Journal of Paleontology 78: 371–387.

[M62] Müller, K. J. 1962. Taxonomy, evolution, and ecology of conodonts. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt W. Miscellanea: Conodonts, Conoidal Shells of Uncertain Affinities, Worms, Trace Fossils and Problematica pp. W83–W91. Geological Society of America, and University of Kansas Press.

[N79] Norris, A. W. 1979. Devonian in the Western Hemisphere. In: Robison, R. A., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt A. Introduction. Fossilisation (Taphonomy), Biogeography and Biostratigraphy pp. A218–A253. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[S88] Sweet, W. C. 1988. The Conodonta: Morphology, taxonomy, paleoecology, and evolutionary history of a long extinct animal phylum. Clarendon Press: Oxford.

[WSQ86] Wang C.-Y., Shi C.-G. & Qu G.-S. 1986. Conodonts and ostracodes from the Devonian “Heitai Formation” of Mishan County, Heilongjiang Province. Acta Micropalaeontologica Sinica 3 (2): 205–214.

[W97] Wang N. 1997. Restudy of thelodont microfossils from the lower part of the Cuifengshan Group of Qujing, eastern Yunnan, China. Vertebrata PalAsiatica 35 (1): 1–17.